The equilibrium thermodynamics of Fe/Mg‐phyllosilicates and carbonates have been investigated using numerical modeling, with emphasis on the effects of evaporation and temperature (hydrothermalism) under conditions related to present‐day and primitive Mars, that is, low or high CO₂ partial pressure, under oxidizing or reducing environments. Findings are discussed in relation to alteration and weathering of minerals found in the Nili Fossae region. Results show that nontronite precipitates at very high water‐to‐precipitate ratio and low temperature, in association with ferrihydrite. During evaporation, this assemblage leads to carbonates: calcite and magnesite, and to low temperature iron‐rich serpentine phyllosilicates such as cronstedtite or berthierine under reducing conditions. At high temperature, the initial paragenesis dominated by nontronite leads to hematite and berthierine at low CO₂ partial pressure, and to talc, magnesite and antigorite at high CO₂ partial pressure. Thus, the Fe/Mg‐smectites, Mg‐carbonate, and Mg‐serpentine found near Nili Fossae may result from several alteration events. Weathering of primitive bedrock formed nontronite, with subsequent or concurrent hydrothermalism leading to Mg‐serpentine. Further carbonation due to CO₂‐rich fluids led to talc, magnesite and to hydrogen/carbon monoxide/methane in the presence of iron, but at relatively low partial pressures (up to 10⁻⁴ bar). Unless the serpentinization process acted for extended periods of time and over a large portion of the martian surface, it is unlikely it significantly contributed to the atmospheric composition, except maybe for H₂. However, such water‐rich active environments with the presence of redox reactions could have been suitable for the potential emergence of biological activity.

中文翻译：

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尼利·福萨和火星的碳酸盐-苯基硅酸盐共生和水蚀环境

使用数值模型研究了Fe / Mg层状硅酸盐和碳酸盐的平衡热力学，重点是在与当前和原始火星有关的条件下，即低或高CO ₂的蒸发和温度（水热）的影响。在氧化或还原环境下的分压。讨论了与尼利福萨地区发现的矿物的变化和风化有关的发现。结果表明，与水铁矿结合，绿脱石在很高的水-沉淀比和低温下沉淀。在蒸发过程中，这种组合会在还原条件下生成碳酸盐：方解石和菱镁矿，并生成低温的富含铁的蛇纹石页硅酸盐，如长硅钙石或berthierine。在高温下，在初始共生由绿脱石导致赤铁矿和磁绿泥石在低的CO为主₂分压，以及滑石，菱镁矿和叶蛇纹石在高CO ₂分压。因此，在尼利福萨附近发现的铁/镁蒙脱石，碳酸镁和蛇纹石镁可能是由几个蚀变事件引起的。原始基岩的风化作用形成了隆脱石，随后的或同时发生的水热作用导致了镁蛇纹石的形成。在铁存在下，但分压相对较低（最高10 ^-4  bar）的情况下，由于富含CO _2的流体导致的进一步碳化导致了滑石，菱镁矿以及氢/一氧化碳/甲烷。除非蛇形化过程在较长的时间段内以及在火星表面的大部分区域上起作用，否则除非对H _2而言，否则不可能对大气成分做出重大贡献。但是，这种存在氧化还原反应的富含水的活跃环境可能适合于潜在的生物活性的出现。